Carbon re-incorporation in phosphorus-doped Si 1− y C y epitaxial layers during thermal annealing

The carbon-incorporation behavior in phosphorous-doped Si-1 C-y(y)/Si (y(1) similar to 0.018, y(2) similar to 0.024) epilayers grown by reduced pressure chemical vapor deposition (RPCVD) has been investigated as a function of annealing temperatures. An abnormal interstitial carbon (C-i) re-incorporation was observed in the initial stage of thermal annealing, introducing an additional tensile strain into the Si-1 C-y(y) epilayers. At higher temperature but below beta-SiC precipitation threshold, almost complete strain relaxation was found. These strain transitions can be attributed to the competitive behavior between Ci re-incorporation and phosphorus deactivation to kick out the substitutional carbon (C-sub) atoms during the post-annealing process. This work demonstrated that Si-1 C-y(y) epilayers grown by RPCVD could keep both enhanced carbon incorporation and nonequilibrium phosphorus activation if the thermal budget is well controlled. (C) 2012 Elsevier B. V. All rights reserved.